The paper industry has for some time needed paper products that are sufficiently strong for their intended application and capable of dispersing quickly and easily. A flushable paper product having both high wet strength and high dispersibility would be useful because such a product would meet the needs of many consumers and markets. For instance, a strong and dispersible bathroom tissue could be easily flushed into septic or sewer systems without clogging the system's pipes.
Currently, we are not aware of any product that offers such benefits. Products made without polymeric strength agents exhibit excellent dispersibility but have poor wet strength. Conversely, paper products made with polymer strength agent have good wet strength but poor to mediocre dispersibility. The advent of “temporary wet strength agents” has improved dispersibility but the available technology is still not sufficiently advanced to meet industry needs and preferences. A truly strong and dispersible flushable product such as bathroom tissue would have great advantages in the marketplace.
U.S. Pat. No. 6,322,665 teaches applying a polymeric anionic reactive compound heterogeneously to a cellulosic fibrous web and curing the compound to crosslink the cellulose fibers. The patent teaches webs that exhibit high wet strength in one direction such as the machine or cross-machine direction, but which readily fail when wet in the orthogonal direction. The patent teaches that flushable products, by virtue of having regions that have not been treated with wet strength agents and specifically with polymeric anionic reactive compounds, have regions that can break apart readily when flushed and sent to a septic system, yet still have wet strength zones to enhance use prior to flushing. Unfortunately, this chemistry contains significant disadvantages. For instance, the polymeric anionic reactive compound must be cured in order to be effective. The polymeric anionic reactive compound produces cellulose-polymer bonds that are less subject to degradation, and thus, more permanent. The patent does not provide guidance about the use of cationic or nonionic strength agents. In fact, the patent expressly discusses the disadvantages of cationic strength agents. Further, the patent does not provide meaningful guidelines about using anionic glyoxylated polyacrylamide polymers, polymers which do not have to be cured. The patent does not provide a comprehensive method that allows the user to control the level of strength and dispersibility of a paper product.
WO 01/38638 A1 teaches the use of an alkaline reagent in wet strength tissue. The document discusses a tissue product comprising a web of fibers, a temporary wet strength agent forming hemi-acetal bonds, and an alkaline reagent. The alkaline reagent is sprayed onto the surface of the sheet in the dry end. The document does not provide meaningful details about how to make a product having both high strength and high dispersibility. The document does not provide guidelines that would enable an artisan to develop a comprehensive method for making paper products with a wide range of different combinations of wet strength and dispersibility.
U.S. Pat. No. 5,952,251 teaches using reinforcing polymer fibers to achieve strength with dispersibility. The patent discusses a paper product having a primary fiber structure which is water dispersible, a secondary fiber structure which delivers strength, and an absorbent material such as pulp fiber. The document does not provide guidelines that would enable an artisan to develop a comprehensive method for making paper products with a wide range of different combinations of wet strength and dispersibility.
The above-mentioned deficiencies are typical in the art.
For the foregoing reasons, there has been an ongoing need to develop a paper product that has both high wet strength and high dispersibility.
For the foregoing reasons, there has been an ongoing need to develop a method for making a paper product having both high wet strength and high dispersibility.